This invention relates to the detection and prevention of infection by a newly discovered etiological agent for non-A, non-B (NANB) hepatitis. In particular it is concerned with making vaccines and conducting immunoassays for this agent or its antibodies.
NANB hepatitis is defined as clinical hepatitis which cannot be attributed to infection by cytomegalovirus, Epstein-Barr virus, or hepatitis A or B.
NANB hepatitis was first identified in transfused individuals. Transmission from man to chimpanzee and serial passages in chimpanzees provided evidence that NANB hepatitis is due to an infectious agent or agents. NANB hepatitis represents up to 90% of post-transfusion hepatitis cases since HBsAg positive blood is no longer used for transfusion. The risk of contracting NANB hepatitis after blood transfusion has been estimated to be close to 10% in the United States. Therefore, it is important to screen the blood of potential donors to detect NANB hepatitis. Further, use of donors vaccinated against NANB hepatitis would serve to reduce the probability of transmitting serum hepatitis.
NANB hepatitis has been found to be associated with a variety of virus-like particles found in serum and tissue extracts. Hollinger et al., in "Proc. Second Symposium on Viral Hepatitis" (San Francisco), p. 699, (1978) report the previous work of others in locations 20-22 nm and 60-80 nm particles associated with NANB hepatitis. Other particIes which have been reported to be associated with NANB hepatitis are (a) small spheres and filaments 15-25 nm in diameter, (b) 35-40 nm diameter virions which resemble the hepatitis B DANE particle, (c) a 27 nm viruslike particle identified in lots of antihemophilic factor and liver tissue from chimpanzees infected with antihemophilic factor ("Morbidity and Mortality Weekly Report" 27 (21) [1978]), and (d) a 20-27 nm diameter particle identified in hepatocytes of infected animals (Shimizu et al., "Science" 205: 197-200 [1979]). In addition, antigen-antibody systems not linked to a definitive particle have been identified as associated with NANB hepatitis (Kabiri et al., "Lancet", Aug. 4, 1979, pp. 221-224; Vitvitski et al., "Lancet", Dec. 15, 1979, pp. 1263-1267; Dienstag et al., "Lancet", June 16, 1979, pp. 1265-1267; and Shirachi et al., "Lancet", Oct. 21, 1978, pp. 853-856).